AIR Analyzes Potential Impact of Super Typhoon Haiyan on Philippines

November 8, 2013

Catastrophe modeling firm AIR Worldwide issued a bulletin shortly before Super Typhoon Haiyan [known locally as Yolanda] came ashore across the central Philippines. As predicted the extremely powerful storm – the 30th tropical cyclone of 2013 – will cause a lot of damage.

AIR said it would affect approximately two-thirds of the country. However, the report also indicated that “insurance penetration” in the areas expected to be the worst affected by the storm are “around 10 percent to 20 percent,” as a result AIR said it “does not expect significant insured losses from this event.”

Haiyan’s central pressure was a very low 895 mb. AIR said sustained wind speeds reached “231 km/h (143.5 mph), and gusts as high as 324 km/h (200 mph),” making the storm the “strongest tropical cyclone of 2013 globally. It will be the strongest to make landfall anywhere in the world since Megi made landfall in the Philippines in 2010 with 10-minute sustained wind speeds of 231 km/h (143.5 mph). Haiyan’s wind speeds are the second highest ever observed in the Northwest Pacific basin, and its central pressure is tied as the 20th lowest.”

AIR Worldwide senior scientist Jason Butke explained: “Haiyan is in a very conducive environment for tropical cyclone development, with sea surface temperatures (SSTs) above 30°C [86° F], ample low-level moisture, and low wind shear. As a result, Haiyan is not forecast to weaken prior to landfall. Wind will be the primary cause of damage but precipitation-induced flooding could occur locally and be severe.

“Haiyan is forecast to weaken slightly as it passes through the central Philippines but will continue moving west-northwest along the southern periphery of the subtropical ridge,” he continued. “After exiting into the South China Sea, Haiyan is forecast to continue to weaken somewhat as it experiences slowly decreasing SSTs before making landfall in Vietnam.”

According to Japan Meteorological Agency (JMA), the forecast intensity when the storm reaches Vietnam is 930 mb, with 10-minute sustained wind speeds of 185 km/h (115 mph), and gusts as high as 259 km/h (161 mph). Precipitation in the wake of the storm is on the order of 150-250 mm (about 6-10 inches) according to the Tropical Rainfall Measuring Mission (TRMM).

Butke noted: “In addition to devastating winds, the storm will bring storm surge to the eastern coast of southern Luzon and the Samar islands, and deposit heavy rain across a wide swath of the central Philippines as it passes approximately 386 km (240 miles) to the south of Manila. This region, recently drenched by a tropical cyclone and still reeling from the 7.1-magnitude earthquake that struck the island of Bohol in October, is home to about 10 million people.”

More than 30 provinces across the country have been alerted to prepare for possible flash floods and landslides. Relief goods and emergency services have been positioned, and thousands of people in vulnerable areas have been evacuated. Schools have closed and airlines have canceled flights.

Butke concluded: “Typhoon Haiyan will impact a region of the Philippines that is largely rural and agricultural, although some cities are in the path of the storm.”

According to AIR, given that the region is generally less urbanized and less accustomed to typhoons, “construction types and standards are lower than those in the northern Islands. While reinforced masonry structures are typical, light materials – such as wood frame with galvanized iron and aluminum roofs are frequently used for residential buildings in these rural areas making them more vulnerable when compared with those in neighboring Manila, Hong Kong, or Taiwan.”

Source: AIR Worldwide

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